Bertha now a third of the way done with SR 99 tunnel

SEATTLE — The new State Route 99 tunnel is now a third of the way done.

On Wednesday, contractors reported the tunnel machine Bertha is entering a planned maintenance stop 120 feet below Spring Street between Alaskan Way and First Avenue, where it will stay for several weeks so crews can do inspections and change out worn tools on the cutterhead.

"We're at a very good point where it's just progressing very steadily, very nicely," said Chris Dixon, project manager with Seattle Tunnel Partners.

Dixon said after a two-year breakdown led to a near-rebuild of the $80 million machine, Bertha is now working well.

"The rebuild worked, yes. The repairs to the TBM were successful," Dixon said.

Dixon said he expects the machine will break through at the end of the tunnel drive early next year.

He expected an updated prediction for when in 2018 the tunnel will open to traffic sometime after the maintenance stop.

Crews have been working two 12-hour shifts five days a week, and building an average of seven concrete tunnel rings each day.

Contractors say the system that monitors ground movement is finding no problems.

"The ground is remaining very, very stable," Dixon said. "It's not moving as we tunnel."

Dixon said the costs of the breakdown and repairs are still being tallied.

Cox Media Group